22. Isdnlog

22.1 Isdnlog (=2.52) shows for a caller two telephone numbers! Which one is correct?

The caller has most likely activated the (costly) feature CLIP (= Calling Line Identification Presentation, no screening), which means any telephone number can be transmitted. See the question "I've heard that actually two Caller IDs are transmitted?".

Andreas Kool akool@Kool.f.EUnet.de wrote on 26 Jan 1997:

In any case, you can only fool software/PBXs that do not evaluate the screening indicator - isdnlog with version 2.52 shows both the correct *and* the faked telephone number.

...CLIP, no screening was actually designed for transmitting internal company numbers in the public network.

22.2 I've set up a script to play sound per cat on /dev/sound or some other device. When several events occur, then there is an error:"Can't open output file '/dev/sound': Device or resource busy"

Only one process at a time can access the sound device. You need an upper instance that coordinates access to the sound device. NAS (network audio system), and rplay can be used for this.

22.3 Isdnlog should call a program with redirected output (e.g. "play anruf.au 2/dev/null" ). Why does ISDN tell me "Can'tstart '/usr/local/bin/play anruf.au 2/dev/null' with execvp()"?

Andreas Kool akool@Kool.f.EUnet.de wrote on 6 Nov 1996:

Because isdnlog is not a (Bourne) shell ;-) isdnlog can only start "real" programs.

Short and sweet: this example has to be saved as an executable (- chmod +x) file in the following way:

#!/bin/sh
/usr/local/bin/play anruf.au 2/dev/null

22.4 When dialing out, the screen goes momentarily black?

This may happen when you start isdnlog with the options "-t 1" or "-t 2", then the time is synchronized with the digital switching station. The screen saver thinks that more than x minutes have passed, which causes a short blackout of the screen.